#pragma once
#include <string>

using namespace std;
class SalesItem
{
public:
	SalesItem();
	virtual ~SalesItem();
    SalesItem& operator=(SalesItem& si);
	string isbn();
	friend ostream& operator<< (ostream& os, SalesItem& si);
	friend istream& operator>>(istream& is, SalesItem& si);
	SalesItem& combine(SalesItem& si);
private:
	string _book_no;
	unsigned int _units_sold = 0;
	double _selling_price = 0.0;
	double _sale_price = 0.0;
	double _discout = 0.0;
};

